Deploy and Verify a Smart Contract with Hardhat

Deploying a Contract Using Hardhat Scripts

This tutorial will walk you through writing and compiling an ERC-721 Solidity smart contract. You’ll then deploy and interact with it on the Hedera network using the Hedera Smart Contract Service (HSCS) and familiar EVM tools like Ethers.js, connecting via the JSON-RPC relay.

What you will accomplish

By the end of this tutorial, you will be able to:

Compile and deploy a smart contract using Hardhat
Interact with a smart contract using Hardhat

Note: This tutorial is currently supported only in the Getting Started JavaScript series and is not available for other languages.

Prerequisites

Before you begin, you should have completed the following tutorial:

Create and Fund a Testnet Account via the Hedera Faucet

Step 1: Project Setup
Step 2: Creating the ERC-721 Contract
Step 3: Deploy Your ERC-721 Smart Contract
Step 4: Minting an ERC-721 Token
Step 5: Verify Your Smart Contract on HashScan

Step 1: Project Setup

Initialize Project

Set up your project by initializing the hardhat project:

mkdir hardhat-erc-721-mint
cd hardhat-erc-721-mint
npx hardhat --init

Make sure to select “Hardhat 3 → Typescript Hardhat Project using Mocha and Ethers.js” and accept the default values. Hardhat will configure your project correctly and install the required dependencies.

🚧 What's new: Hardhat 2 → 3

Key differences in Hardhat 3:

compile → build
npx hardhat compile is now npx hardhat build. This is the big one. The v3 migration guide explicitly shows using the build task.
project init switch
v2 commonly used npx hardhat or npx hardhat init to bootstrap. In v3 it’s npx hardhat --init.
keystore helper commands are new
v3’s recommended flow includes a keystore plugin with commands like npx hardhat keystore set HEDERA_RPC_URL and npx hardhat keystore set HEDERA_PRIVATE_KEY. These weren’t standard in v2.
Foundry-compatiable Solidity tests
In addition to offering Javascript/Typescript integration tests, Hardhat v3 also integrates Foundry-compatible Solidity tests that allows developers to write unit tests directly in Solidity
Enhanced Network Management
v3 allows tasks to create and manage multiple network connections simultaneously which is a significant improvement over the single, fixed connection available in version 2. This provides greater flexibility for scripts and tests that interact with multiple networks.

📚 Learn more from the official Hardhat documentation.

Install Dependencies

Next, install the required dependencies:

npm install @openzeppelin/contracts

Before we make any changes to our Hardhat configuration file, let’s set some configuration variables we will be referring to within the file later.

When you set up your keystore for the first time, you’ll be asked to create a keystore password. Save this password securely because you’ll need it anytime you set or reset a variable.

# If you have already set this before, please use the --force flag
npx hardhat keystore set HEDERA_RPC_URL

For HEDERA_RPC_URL, we’ll have https://testnet.hashio.io/api

# If you have already set this before, please use the --force flag
npx hardhat keystore set HEDERA_PRIVATE_KEY

For HEDERA_PRIVATE_KEY, enter the HEX Encoded Private Key for your ECDSA account from the Hedera Portal.

Note

Hashio is intended for development and testing purposes only. For production use cases, it’s recommended to use commercial-grade JSON-RPC Relay or host your own instance of the Hiero JSON-RPC Relay.

Configure Hardhat

Update your hardhat.config.ts file in the root directory of your project. This file contains the network settings so Hardhat knows how to interact with the Hedera Testnet. We’ll use the variables you’ve stored in your .env file.

hardhat.config.ts

import type { HardhatUserConfig } from "hardhat/config";

import hardhatToolboxMochaEthersPlugin from "@nomicfoundation/hardhat-toolbox-mocha-ethers";
import { configVariable } from "hardhat/config";

const config: HardhatUserConfig = {
  plugins: [hardhatToolboxMochaEthersPlugin],
  solidity: {
    profiles: {
      default: {
        version: "0.8.28",
      },
      production: {
        version: "0.8.28",
        settings: {
          optimizer: {
            enabled: true,
            runs: 200,
          },
        },
      },
    },
  },
  networks: {
    testnet: {
      type: "http",
      url: configVariable("HEDERA_RPC_URL"),
      accounts: [configVariable("HEDERA_PRIVATE_KEY")],
    },
  },
};

export default config;

You can verify the connection by running:

npx hardhat console --network testnet

This command launches an interactive JavaScript console connected directly to the Hedera testnet, providing access to the Ethers.js library for blockchain interactions. If you successfully enter this interactive environment, your Hardhat configuration is correct. To exit the interactive console, press ctrl + c twice. We won’t be using ignition and we will be removing the default contracts that come with the Hardhat default project, so we will remove all the unnecessary directories and files first:

rm -rf contracts/* scripts/* test/*
rm -rf ignition

Step 2: Creating the ERC-721 Contract

Create a new Solidity file (MyToken.sol) in our contracts directory:

contracts/MyToken.sol

// SPDX-License-Identifier: MIT
// Compatible with OpenZeppelin Contracts ^5.0.0
pragma solidity ^0.8.28;

import {ERC721} from "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";

contract MyToken is ERC721, Ownable {
    uint256 private _nextTokenId;

    constructor(address initialOwner)
        ERC721("MyToken", "MTK")
        Ownable(initialOwner)
    {}

    function safeMint(address to) public onlyOwner returns (uint256) {
        uint256 tokenId = _nextTokenId++;
        _safeMint(to, tokenId);
        return tokenId;
    }
}

This contract was created using the OpenZeppelin Contracts Wizard and OpenZeppelin’s ERC-721 standard implementation with an ownership model. The ERC-721 token’s name has been set to “MyToken.” The contract implements the safeMint function, which accepts the address of the owner of the new token and uses auto-increment IDs, starting from 0. Let’s compile this contract by running:

npx hardhat build

This command will generate the smart contract artifacts, including the ABI. We are now ready to deploy the smart contract.

Step 3: Deploy Your ERC-721 Smart Contract

Create a deployment script (deploy.ts) in scripts directory:

scripts/deploy.ts

import { network } from "hardhat";

const { ethers } = await network.connect({
  network: "testnet",
});

async function main() {
  // Get the signer of the tx and address for minting the token
  const [deployer] = await ethers.getSigners();
  console.log("Deploying contract with the account:", deployer.address);

  // The deployer will also be the owner of our NFT contract
  const MyToken = await ethers.getContractFactory("MyToken", deployer);
  const contract = await MyToken.deploy(deployer.address);

  await contract.waitForDeployment();

  const address = await contract.getAddress();
  console.log("Contract deployed at:", address);
}

main().catch(console.error);

In this script, we first retrieve your account (the deployer) using Ethers.js. This account will own the deployed smart contract. Next, we use this account to deploy the contract by calling MyToken.deploy(deployer.address). This passes your account address as the initial owner and signer of the deployment transaction. Deploy your contract by executing the script:

npx hardhat run scripts/deploy.ts --network testnet

Copy the deployed address—you’ll need this in subsequent steps.

The output looks like this:

~/projects/hardhat-erc-721-mint-burn >> npx hardhat run scripts/deploy.ts --network testnet
Compiling your Solidity contracts...
Compiled 1 Solidity file with solc 0.8.28 (evm target: cancun)

Deploying contract with the account: 0xA98556A4deeB07f21f8a66093989078eF86faa30
Contract deployed at: 0x6035bA3BCa9595637B463Aa514c3a1cE3f67f3de

Step 4: Minting an ERC-721 Token

Create a mint.ts script in your scripts directory to mint an NFT. Don’t forget to replace the <your-contract-address> with the address you’ve just copied.

scripts/mint.ts

import { network } from "hardhat";

const { ethers } = await network.connect({
  network: "testnet",
});

async function main() {
  const [deployer] = await ethers.getSigners();

  // Get the ContractFactory of your MyToken ERC-721 contract
  const MyToken = await ethers.getContractFactory("MyToken", deployer);

  // Connect to the deployed contract
  // (REPLACE WITH YOUR CONTRACT ADDRESS)
  const contractAddress = "<your-contract-address>";
  const contract = MyToken.attach(contractAddress);

  // Mint a token to ourselves
  const mintTx = await contract.safeMint(deployer.address);
  const receipt = await mintTx.wait();
  console.log("receipt: ", JSON.stringify(receipt, null, 2));
  const mintedTokenId = receipt?.logs[0].topics[3];
  console.log("Minted token ID:", mintedTokenId);

  // Check the balance of the token
  const balance = await contract.balanceOf(deployer.address);
  console.log("Balance:", balance.toString(), "NFTs");
}

main().catch(console.error);

The code mints a new NFT to your account ( deployer.address ). Then we verify the balance to see if we own an ERC-721 token of type MyToken. Mint an NFT:

npx hardhat run scripts/mint.ts --network testnet

Expected output:

~/projects/hardhat-erc-721-mint-burn >> npx hardhat run scripts/mint.ts --network testnet
Compiling your Solidity contracts...

Nothing to compile

receipt:  {
  "_type": "TransactionReceipt",
  "blockHash": "0x110b2de909e2f4d515b76de4ffd7a8a9f4c3e68c79f8aa083f9baf2a7d082a5c",
  "blockNumber": 23836191,
  "contractAddress": "0x6035bA3BCa9595637B463Aa514c3a1cE3f67f3de",
  "cumulativeGasUsed": "800000",
  "from": "0xA98556A4deeB07f21f8a66093989078eF86faa30",
  "gasPrice": "350000000000",
  "blobGasUsed": null,
  "blobGasPrice": null,
  "gasUsed": "800000",
  "hash": "0xb0a67ee89e224208599b29a71bc5de1abc5aba4cf64553893aaf0aeb051f7a91",
  "index": 9,
  "logs": [
    {
      "_type": "log",
      "address": "0x6035bA3BCa9595637B463Aa514c3a1cE3f67f3de",
      "blockHash": "0x110b2de909e2f4d515b76de4ffd7a8a9f4c3e68c79f8aa083f9baf2a7d082a5c",
      "blockNumber": 23836191,
      "data": "0x",
      "index": 0,
      "topics": [
        "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef",
        "0x0000000000000000000000000000000000000000000000000000000000000000",
        "0x000000000000000000000000a98556a4deeb07f21f8a66093989078ef86faa30",
        "0x0000000000000000000000000000000000000000000000000000000000000000"
      ],
      "transactionHash": "0xb0a67ee89e224208599b29a71bc5de1abc5aba4cf64553893aaf0aeb051f7a91",
      "transactionIndex": 9
    }
  ],
  "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000008000000000000002001000000000000000000000000000000020000000000000000000800000000000000000000000010000000000000000000000400000000020000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000003000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000000",
  "root": "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
  "status": 1,
  "to": "0x6035bA3BCa9595637B463Aa514c3a1cE3f67f3de"
}
Minted token ID: 0x0000000000000000000000000000000000000000000000000000000000000000
Balance: 1 NFTs

Step 5: Verify Your Smart Contract on HashScan

After deploying your smart contract, you should verify the source code on HashScan. Programmatic verification is the most reliable and efficient method, especially for complex or upgradeable contracts.

Install the Verification Plugin

Hardhat uses the dedicated hashscan-verify plugin to interface with the HashScan Smart Contract Verifier API (which is based on the Sourcify standard). Install the plugin in your project:

npm i -D hashscan-verify

Configure Hardhat for Verification

Import the plugin in your hardhat.config.ts file:

import hashscanVerify from "hashscan-verify"; // <--- ADD THIS LINE

import type { HardhatUserConfig } from "hardhat/config";
import hardhatToolboxMochaEthersPlugin from "@nomicfoundation/hardhat-toolbox-mocha-ethers";
import { configVariable } from "hardhat/config";

const config: HardhatUserConfig = {
  plugins: [hardhatToolboxMochaEthersPlugin, hashscanVerify], // ADD TO PLUGIN LIST
  solidity: {
    profiles: {
      default: {
        version: "0.8.28"
      },
      production: {
        version: "0.8.28",
        settings: {
          optimizer: {
            enabled: true,
            runs: 200
          }
        }
      }
    }
  },
  networks: {
    testnet: {
      type: "http",
      url: configVariable("HEDERA_RPC_URL"),
      accounts: [configVariable("HEDERA_PRIVATE_KEY")]
    }
  }
};

export default config;

Run the Verification Command

The plugin adds the hashscan-verify task to Hardhat. The basic command structure is:

npx hardhat hashscan-verify <CONTRACT_ADDRESS> \
  --contract "<PATH_TO_CONTRACT>:<CONTRACT_NAME>" \
  --network <NETWORK_NAME>

Example: Verifying Your MyToken Contract

Using the contract address from your deployment:

# Replace with your actual deployed contract address
CONTRACT_ADDRESS="0x6035bA3BCa9595637B463Aa514c3a1cE3f67f3de"

npx hardhat hashscan-verify "$CONTRACT_ADDRESS" \
  --contract "contracts/MyToken.sol:MyToken" \
  --network testnet

The plugin will handle uploading the source code and metadata to the HashScan verifier. You should receive a Full Match verification status. Troubleshooting Verification

Issue	Solution
Verification Fails/Mismatch	Ensure your local compilation settings (Solidity version, optimizer runs, viaIR) exactly match the settings used for deployment. Run `npx hardhat clean && npx hardhat compile` before retrying.
Constructor Arguments Error	If your contract has constructor arguments, pass them as positional arguments after the contract name in the verification command.
Hardhat Keystore Password Prompt	The task may prompt for your Hardhat keystore password if it needs to sign a transaction to read deployment details. Enter it when prompted.

Congratulations! 🎉 You have successfully learned how to deploy and verify an ERC-721 smart contract using Hardhat, OpenZeppelin, and Ethers. Feel free to reach out in Discord!

Next Steps

Learn how to add Access Control, Pause, and Transfer ERC-721 tokens
Check out OpenZeppelin ERC-721 Documentation
See the full code in the Hedera-Code-Snippets Repository

Writer: Kiran, Developer Advocate

Github | Linkedin

Editor: Krystal, DX Engineer

Github | X

Editor: Logan, Software Engineer II

GitHub | LinkedIn

Editor: Jake, DevRel Engineer

GitHub | X

Editor: Michiel, DevRel Engineer

GitHub | LinkedIn

​Deploying a Contract Using Hardhat Scripts

​What you will accomplish

​Prerequisites

​Table of Contents

​Step 1: Project Setup

​Initialize Project

​Install Dependencies

​Note

​Configure Hardhat

​Step 2: Creating the ERC-721 Contract

​Step 3: Deploy Your ERC-721 Smart Contract

​Step 4: Minting an ERC-721 Token

​Step 5: Verify Your Smart Contract on HashScan

​Install the Verification Plugin

​Configure Hardhat for Verification

​Run the Verification Command

​Example: Verifying Your MyToken Contract

​Next Steps

Writer: Kiran, Developer Advocate

Editor: Krystal, DX Engineer

Editor: Logan, Software Engineer II

Editor: Jake, DevRel Engineer

Editor: Michiel, DevRel Engineer

Deploying a Contract Using Hardhat Scripts

What you will accomplish

Prerequisites

Table of Contents

Step 1: Project Setup

Initialize Project

Install Dependencies

Note

Configure Hardhat

Step 2: Creating the ERC-721 Contract

Step 3: Deploy Your ERC-721 Smart Contract

Step 4: Minting an ERC-721 Token

Step 5: Verify Your Smart Contract on HashScan

Install the Verification Plugin

Configure Hardhat for Verification

Run the Verification Command

Example: Verifying Your MyToken Contract

Next Steps